Railroad lines are comprised of spaced cross ties with superimposed plates, which carry two top spaced rails. The space of the rails determines the gauge of the railroad line. The ties traditionally rest upon ballast, which has been compacted and graded (contoured) to define the path of the railroad line, including axial slope as appropriate and transverse banking to accommodate turning in respect to a change in direction of the rails and ties.
While concrete ties are sometimes used, wooden ties, usually treated with a chemical such as creosote, have historically been used. The present invention is concerned with wooden railroad ties.
Each wooden railroad tie receives two steel railroad plates on the top of the tie. Each plate is secured in position by steel spikes driven into the associated wooden railroad tie through apertures in the plate. Ultimately, at least one field spike and one gauge spike is driven through apertures in the associated plate into the wooden tie until the head of the spike is either contiguous with the top surface of the associated plate or is above the associated plate a distance sufficient to accommodate placement of one side of the lower flange of a rail beneath the head of that spike. This creates a fixed and permanent relationship between the plate and the wooden railroad tie. At the time of rail installation, other spikes are driven through the remaining apertures in each plate. Two apertures exist in each of two central parallel flanges or ridges of each plate and one aperture in each of two plate regions spaced from the flanges. The flanges of each plate are parallel to the direction of the railroad line and perpendicular to the axis of the associated tie. All of the spikes driven through apertures in the flanges of the associated plate into the wooden tie ultimately become contiguous with the top surface of one or the other of two oppositely-directed base, lower or bottom flanges of a railroad rail to hold the rail in a secure position on the plate between the flanges. The rail is thus securely positioned between and parallel to the plate flanges.
In earlier times, it was commonplace to assemble plates, ties, spikes and rails at the site of a railroad line being constructed or repaired. This approach is sometimes still used. Precision in correctly locating each plate on top of the associated tie presented significant problems in the field. Accuracy in field placement of the plates on the ties has been particularly difficult when the plates were worn between the flanges due to prior use.